Multifunctional Polyvinyl Alcohol/Chitosan Composite Film Containing L-Cysteine and Pomegranate Peel Carbon Dots for...

Currently, the resource wastage and safety hazards caused by fruit and vegetable spoilage are becoming increasingly prominent. Developing green, efficient, and non-toxic novel preservation materials has emerged as a hot spot in fruit and vegetable research. Based on this, this study utilized pomegranate peel as a raw material to prepare spherical multifunctional carbon dots (P-CDs) with an average particle size of 1.98 ± 0.58 nm through a one-step hydrothermal reaction. Subsequently, P-CDs were co-incorporated with L-cysteine (L-Cys) into a polyvinyl alcohol (PVA) and chitosan (CS) matrix to construct a novel composite coating material with combined antibacterial, antioxidant, and preservation functions. Experimental results demonstrate that P-CDs exhibit outstanding antioxidant activity and antibacterial performance. Compared to PVA/CS film, the P-CDs/L-Cys/PVA/CS film exhibited a 6.55 MPa increase in tensile strength and significantly enhanced thermal stability. Furthermore, the incorporation of P-CDs and L-Cys markedly boosted the PVA/CS film's antioxidant activity (97% for ABTS; 85.69% for DPPH), antibacterial performance, and ultraviolet (UV) shielding capability. Coating cherry tomatoes with the P-CDs/L-cysteine/PVA/CS composite extended their shelf life by 6 days. This composite coating material exhibits preliminary biocompatibility and eco-friendly properties, aligning with green sustainable development needs and offering a novel potential solution for food preservation technology, while its practical applicability to food safety requires further comprehensive verification.